Originally Posted by DanOrion
The safest IV and higher boating is: A good crew that you know, running a river that they know, with everyone boating around their comfort zone, and everyone making well-thought decisions about what to run and what to walk. It's about the people more than the run.
Originally Posted by UserName
i think this question is answered in the definitions of the classes.
These are good and obvious answers, along with some of the others. Which is why a few us answered with specific runs in the sense of "relatively speaking" or "all things being equal". We all know that class V has more general inherent risks than class IV, but it doesn't tell the whole story. Maybe if we look at this as a formula, based on the AWA ratings article
The "Flaco Scale" of the Relative safety of a run = (DM) x (C+R+S)
- DM = Difficulty of crux moves (class I through V)
- C =consequences of an missed line (sieve, cave, strainer). Pick a # system, I'll offer 1-3 good-to-bad.
- R = remoteness of run (accessibility to rescue, 1-3)
- S = ability to set safety in red zone (1-3)
So the Flaco Scale might range from an absolute low-end value of 1 (roadside Class I riffles) to a high end of 45 (Remote class V with bad consequences & sketch safety). There are other variables - crew, water levels, temps, etc, but I'll exclude them for brevity)
For example - Two class V-ish 20 footers: Adrenaline Falls on Lime & Entrance on Vallecito (Let's assume medium flows). Adrenaline has a super-squirrelly 5' entrance that flips boaters & generally takes folks offline 50% of the time before dropping the 20'. Conversely, Entrance has no corresponding challenging features before the drop's lip and a clear visual of the line. (I know this is debatable, but let's speak relatively for a minute)
The bottom of Adrenaline is a clean pool, easy to set safety at the top and bottom. A swim in the LZ will hurt your pride, but you'll retrieve your boat and gear shortly in the slack pool, and you can hike your ass out of the drainage to LC road if you've dislocated a shoulder or had enough.
A missed line in Entrance can put you and your gear behind the falls, where you could find yourself in deep shit, and your crew has to put themselves in considerable danger to help get you out. And you're in a significantly isolated gorge at that point; likely requiring professional help to get out.
Adrenaline gets a rating of 5 x (1+2+1) = 20
Entrance gets a rating of 5 x (3+3+3) = 45
For shits and giggles, Skull in Westwater @20K gets this rating from me:
3 x (2+3+2) = 21
. Yeah - a class III is 'more dangerous' than Adrenaline. But if you miss the III move and get a swimmer with a dislocated shoulder in the Room of Doom, you don't have great safety/recovery options. You have to contend with Shock Rock, and his boat is probably in Moab by the time you get him out. Then he has a 7 mile hike down the Kokipelli. One of the closest calls I've ever seen was a near-flush drowning that started in class III Funnel Falls. Safety (throw ropes on the raft) failed, and getting a swimmer to safety, in heavy class III with no eddies, was pretty desperate. And if we hadn't had raft support, we would have had a 2 day ordeal to get the guy out of the canyon.
Range by class:
Class I = 1 to 3
Class II = 6 to 18
Class III = 9 to 27
Class IV = 12 to 36
Class V = 15 to 45
I'll allow that if a V rapid shakes out to be a 15 on the scale, most folks will call it "IV+"; just because the consequences are relatively light. Realistically speaking, though, a V rapid like Rigor Mortis gives many of us the willies because it's huge & tricky to run correctly; but it's also free of any sieves, you can get a rope to someone quickly, and it's on Hwy 6. That's why guys like Rolf have fired it up with inner tubes. That ain't gonna happen on Entrance at 2.1'.
Now someone can proceed to destroy this rough model, and scream how ridiculous it is because I didn't account for whether the team ate their Wheaties this morning.